Color photographic process and product



Jan. 4, 1955 LAND 2,698,798

COLOR PHOTOGRAPHIC PROCESS AND PRODUCT Filed May 21, 1949 I {huge-Receiving Layer Comqining oxidizing Agcnl Permeable Slrulum Conluiner Layer for Coupler r x Emulsic" LYer Layer for Developing Agenl Supporl Image -Receiving Layer Permeable Mclerial Conlaining oxidizing Agenl 24 Emulsion Layer 25 Layer for Coupler 23 Permeable Slrqlum 22 Layer for Developing Agenr 2Q Supporl FlG. 2

INVENTOR 5M M W W wow y W United States Patent Edwin H. Land, Cambridge, Mass.,'assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application May 21, 1949, Serial No. 94,647

17 Claims. (Cl. 95-8) This invention relates to the art of photography and more particularly to novel processes for the formation of dye images and to film units for use with such processes.

An object of the present invention resides in improved techniques for forming a dye positive image of a negative latent image contained in a photosensitive silver halide emulsion layer of a photographic element by introducing materials, capable of entering into a dye-forming reaction, into said emulsion layer from solution in a liquid which is permeated into said element but which is incapable of entering into said reaction until it has been imbibed into all permeable layers of said element and has been modified within the element by solution therein of said materials whereby to develop silver and image dye in the emulsion layer, and to form in said emulsion layer an imagewise distribution of said materials for transport in solution to a permeable, positive image-receiving layer where said transferred materials are reacted to provide a dye positive image in said image-receiving element.

Another object of the invention is to provide a process for forming a positive image in color, from a latent negative image contained in a silver halide emulsion layer of a photosensitive element, by absorbing into the photosensitive element a liquid and by bringing said liquid into contact with a developing agent only after the liquid has permeated through the emulsion layer and into contact with a coupler material at some stage other than during its passage through the emulsion layer whereby to distribute developing agent and coupler material in the emulsion layer and to develop latent image to silver and form a dye image in situ therewith while providing an imagewise distribution of unreacted developing agent and unreacted coupler material in the emulsion layer, and utilizing the imagewise distribution of unreacted developing agent and unreacted coupler material to form a positive dye image.

Still another object of the invention is the provision of a process of the character described for forming positive images in color which make use of a photosensitive element having a silver halide emulsion layer in which a latent negative image is formed and, in superposed relation to the emulsion layer, a permeable layer containing a color-forming developing agent and another permeable layer containing coupler material reactable with oxidized developing agent to form image dye and wherein liquid. which is a solvent for developing agent and for coupler material, is introduced into the photosensitive element by absorption thereof from a side of said element removed from that layer of the element which contains developing agent as by spreading said liquid in a layer between and in contact with a sheet material comprising an image-carrying layer and said side of the photosensitive element and wherein the developing agent is dissolved in liquid permeated into the photosensitive element substantially only after the liquid has penetrated through the emulsion layer.

Further objects of the invention are to provide a photographic product making use of a photosensitive element having a silver halide emulsion layer and, in superposed relation thereto, a permeable layer which contains a color-farming developing agent and another permeable layer which contains a coupler material reactable with oxidized developing agent to form image dye, a base layer adapted to be associated with the photosensitive element for receiving a transfer image, and a container holding a liquid solvent for the developing agent and for the con- 2,698,798 Patented Jan. 4, 1955 pler material; and to provide a photographic product of the character described wherein the layer which contains coupler material is so positioned that it will be located directly adjacent the base or image-receiving layer when the photosensitive element and the base layer are in superposed position, especially film units wherein the layer which contains developing agent is placed on the side of the emulsion layer which is adapted to be located most distant from the base layer; as well as to provide a photographic product such as that set forth wherein the developing agent and the coupler material are each incorporated in a layer of a material which is water insoluble but is alkali soluble, and also wherein the base or image-receiving layer has a coating of a permeable material arranged in the form of a stratum on the surface thereof adapted to be located directly adjacent the photo sensitive element and also has an oxidizing agent incorporated in the base layer or in said permeable stratum.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the product possessing the features, properties and the relation of components and the processes involving the several steps and the relation and the order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

Figure 1 is a diagrammatic cross-sectional view of a photographic product forming one embodiment of this invention and also diagrammatically shows the product in the course of being processed; and

Fig. 2 is a diagrammatic cross-sectional view of another embodiment of film unit or photographic product.

In general, the photographic process and products disclosed herein, as in my application Serial No. 9,527, filed February 19, 1948, for Photographic Process and Product, now Patent No. 2,559,643, are concerned with the treatment of a latent negative image in a photosensitive silver halide emulsion layer whereby to provide a stable dye positive image thereof in or on another layer hereinafter referred to as an image-carrying layer or base layer.

In the just-mentioned application Serial No. 9,527, I disclose a process adapted to be eifected with negative material in the form of a photosensitive element or sheet which has a photosensitive silver halide emulsion layer and which has a color former or coupler and/or a secondary color-forming developing agent incorporated in some permeable layer of the element other than the emulsion layer. A positive dye image of a latent image contained in the emulsion layer of the negative element is provided by spreading a liquid-processing composition in contact with and between the photosensitive element and a permeable image-receiving layer for permeation into the negative element. The liquid-processing composition is incapable, at the time it is spread, of creating a dye on or in the image-carrying layer and must be modified within the negative sheet material by dissolution therein of at least one component capable of entering into a dye-forming reaction upon the carrying out of an oxidation reaction. I have found that this practice enhances positive image quality over that obtained by procedures wherein the liquid-processing composition, at the time which it is spread, comprises an alkaline aqueous solution of a coupler and a secondary color-forming developing agent.

Under these practices, the liquid composition permeates into the negative sheet material and developing agent, dissolved in liquid composition within the photosensitive element, reduces the exposed silver halide of the latent image to metallic silver and the portions of the developing agent which are oxidized, as a result of silver development, react with the coupler in solution and form a dye image which is coextensive with the silver image. The unreacted developing agent and coupler in the remaining solution provide positive image-forming components which are transferred by diffusion from the photosensitive element to the image-carrying layer and form thereon an imagewise distribution of unreacted developing agent and unreacted coupler which, upon oxidation of the unreacted developing agent, eifect formation of the desired dye positive image in the image-carrying layer. Oxidation of the unreacted developing agent to cause the desired coupling reaction may be eifected by an oxidizing agent incorporated in the image-carrying layer or the coupling may be carried out by aerial oxidation of the developing agent after formation on the image-carrying layer of the imagewise distribution of the unreacted developing agent and unreacted color former.

The present invention is concerned with the improvement of these just described practices and the products utilized to carry them into effect whereby to achieve improved positive image rendition and pictorial quality. To accomplish this improvement, use is made of procedure wherein developing agent is initially made available to liquid-processing composition which has permeated through the emulsion layer of a negative photographic element after being spread between said negative element and a positive image-receiving element or base layer arranged in superposed relation with respect to the negative element, and wherein both developing agent and color-former material are made available to the emulsion layer of the photographic element for negative image formation by liquid processing composition which has permeated through the emulsion.

These steps may be carried out by using a film unit having a negative sheet material or photosensitive element comprising at least a silver halide emulsion layer and two relatively permeable layers, one of said permeable layers being preferably located on one side of the emulsion layer and having a color former or coupler material distributed therein and the other permeable layer being located on the other side of the emulsion layer and having a color-forming developing agent distributed therein. Preferably, the layer containing the color-forming developing agent is located in back of the emulsion layer, i. e., on the side of the emulsion layer which is adapted to be located most distant from the receiving sheet material when the photosensitive element and the image-receiving material are in superposed relationship to each other while the permeable layer in which coupler material is incorporated is arranged for location intermediately of the emulsion layer and the image-carrying layer of the positive or image-receiving sheet material.

Fig. 1 shows a preferred type of film unit with which the practices of the invention may be carried out. The product of Fig. 1 employs a negative sheet material or photosensitive element comprising a support 11 which supports, in the order named, a permeable layer 12 containing a color-forming developing agent, a photosensitive silver halide emulsion layer 14 and a permeable layer 15 containing a color former or coupler. The film unit of Fig. 1 also employs a positive sheet material or image-receiving element 16 comprising an image-receiving or base layer 17 of opaque or transparent material containing an oxidizing agent and having its surface coated with a thin layer or stratum 18 of a permeable material such as a gelatin. As shown in Fig. l the negative material 10 and the positive image-receiving sheet 16, for the purpose of positive image formation, are adapted to be placed in superposed relation and are arranged so that the coating or stratum 18 of the positive material is adjacent the layer 15 which contains the coupler. Therefore, in this embodiment, the layer with coupler material therein is located intermediately of the emulsion layer and the image-receiving layer when the positive and negative elements of the film unit are in overlying relation. If desired, the image-receiving layer 17 may be mounted on a layer comprising a conventional photographic support.

By the present invention, the liquid composition, when spread between the photographic element and the negative image-carrying layer of the film unit, is incapable of entering into an image-forming reaction. This condition of the liquid composition exists in the product of Fig. 1 during the initial permeation of the liquid through the layer of coupler material and through the emulsion layer. In fact, in Fig. 1, the liquid composition is incapable of entering into an image-forming reaction until the container.

it has dissolved developing agent in the layer in back of the emulsion and cannot develop latent image until it has transported dissolved developing agent into the emulsion layer.

An imagewise distribution of unreacted developing agent and unreacted coupler material is provided in the emulsion layer 14 as a result of the development of the latent image to silver and the formation of a dye image in situ therewith. This imagewise distribution of unreacted developing agent and coupler material is transferred from the emulsion layer by imbibition to the base layer 17 which is in such close proximity to the photosensitive element as to receive a depthwise diffusion of liquid from the emulsion layer without appreciably disturbing the imagewise distribution of the unreacted components contained in the liquid. Aerial or other oxidation of the unreacted developing agent which is distributed in the image-carrying layer is utilized to etfect formation of the dye positive image in the image-carrying layer.

In the film unit of Fig. 1, a fracturable container 19 adapted to carry the liquid-processing composition is shown as positioned transversely of and adhered to layer 15 in which the coupler is dispersed. If desired, the container 19 may be adhered to the surface of the positive sheet material 16. Container 19 is of a length approximating the width of the film unit and is constructed to carry sufiicient liquid to efiect negative image formation in an exposed image area of the emulsion layer 14 and positive image formation in the corresponding image area of the image-receiving layer 17. In use, a container 19 is adapted to be positioned between the image-receiving layer and the emulsion layer so that it will lie adjacent the edges of the corresponding image areas in these layers which are to be processed by the liquid contents of When the film unit is of the roll film type, a plurality of containers are employed, one for each corresponding pair of successive image areas in the emulsion layer and in the base layer.

In all products employed in the practice of the invention, it is preferable to expose the negative material or photosensitive element 10 from the emulsion side, i. e., the side of the emulsion most distant from the support 11, to prevent geometrical reversal of the positive image and to maintain good definition. It is therefore desirable to hold the photosensitive element 10 and positive sheet material 16 together at one end thereof by fastening means, not shown but comprising hinges, staples, or the like, in such manner that the photosensitive element 10 and negative material 16 may be spread apart as shown in Fig. 1, yet may also be brought together as also indicated towards the left in Fig. 1.

When the film unit is of the roll film type, the photosensitive element 10 and the positive image-receiving sheet 16 are wound into separate rolls and the free ends of said rolls are connected together, in the manner described, and are threaded through pressure rolls 9 which form a part of camera apparatus not illustrated in detail. This permits the photosensitive element 10 and the positive image-receiving sheet 16 to be arranged in spread apart relation so that the individual image areas of the photosensitive element 10 may be successively located within the exposure chamber of suitable camera apparatus and with the corresponding image areas of the positive sheet material located outside of the exposure chamber whereby the photosensitive element 10 may be exposed through the emulsion side thereof. With regard to suitable camera apparatus, reference is made to the Polaroid Land Camera, Model 95, as well as to Patent No. 2,435,717, issued February 10, 1948, to Edwin H. Land, for Developing Camera Utilizing a Film, Another Sheet Material, and a Fluid Processing Agent.

Following exposure, a tensional or pulling force is applied to the portion of the film unit which extends to the left of the pressure rolls 9 whereby to pull the exposed image area of the photosensitive element 10 and the corresponding image area of the positive sheet material 16 through the rolls 9. These pressure rolls fracture a container 19, as it passes therethrough, by the application of mechanical stress and cause the liquid contents of the container to be released and spread between the negative and positive sheet materials. At the same time the pressure rolls 9 cause the photosensitive element 10 and the positive sheet material 17 to be brought together as illustrated to the left of the rolls 9. Thus, the processing of the film unit is made possible either in a hand camera or as the result of ejection of a film unit from a hand camera.

That the film unit of Fig. 1 permits the principles of the invention to be carried out will be evident. Separation of the coupler material and the developing agent in different layers makes it necessary for liquid-processing composition, released on fracture of a container 19, to permeate through the layer of color former and the emulsion layer 14 and into the layer 12 of developing agent before it becomes capable of entering into a dyeforming reaction. Under these conditions, silver development and dye formation in the emulsion can substantially only be initiated by the return to the emulsion 14 of liquid composition which has permeated into the layer 12 and which has dissolved developing agent in layer 12. Furthermore, developer and dye stain in the positive image is substantially avoided by placing the developing agent at a location where it can be reached for solution only by liquid composition which has passed through the emulsion layer, or to put it another way, developing agent in solution must first pass through the emulsion before the developing agent can contact the positive sheet.

The support 11 of the negative sheet material 10, of the film unit illustrated in Fig. 1, comprises any conventional photographic support material. The negative sheet material is manufactured by successively casting layers 12, 14 and 15 on the support 11. Layer 14 comprises any conventional silver halide emulsion, for example a gelatin emulsion of silver halide. Water or moisture contained in the emulsion when cast will permeate into the layer 12 the latter is of a Water-soluble or water-permeable nature and may cause developing agent from layer 12 to be introduced into the emulsion layer 14. Similarly, if the layer 15 is of a water-soluble or water-permeable character, moisture contained in the emulsion layer may penetrate into the layer 15 if it is cast upon the emulsion layer before the latter is thoroughly dry and may cause coupler material from the layer 15 to be introduced into the emulsion layer 14 and even into the layer 12 which contains developing agent.

This is undesirable since developing agents are readily susceptible to oxidation in aqueous solution and when oxidized not only act to desensitize an emulsion but also lose their effectiveness to develop latent image. Furthermore, the presence of a color former in a layer containing developing agent renders the developing agent very susceptible to auto-oxidation.

For the reasons just noted, the color former material and the developing agent are each incorporated in an individual layer of an enteric material. By enteric material, I mean a material which is water insoluble and which is alkali soluble. A preferred example of an enteric material is cellulose acetate hydrogen phthalate. As other examples of suitable enteric materials. mention may be made of any easily saponified, organic film-forming material such as shellac and japan wax. The coupler and the developing agent may be incorporated in individual solutions of an enteric material which are of an appropriate viscosity to permit layers 12 and 15 to be formed by castin g. These solutions are formed by dissolving the enteric material and the coupler or developing agent in organic solvents which are substantially free of Water. Gelatin is substantially impermeable to solvents of this character which also possess the abilitv to protect a developing agent dissolved therein from oxidation.

Generally speaking, coupler material incorporated within a photosensitive emulsion laver of the character described will have no serious effect upon the emulsion. However, obiections to this practice arise in conjunction with the present invention. Alkali solutions and organic solvents, such as acetone in which coupler material is dissolved, are emploved in general for introducing a coupler into a cast emulsion, as by imbibition, or may be added to an emulsion mixture before the emulsion is east. It is to be kept in mind that an enteric material is permeable to both alkali and organic solvents and also that if the coupler solution contains water it may be permeated into gelatin. Once introduced into the emulsion, such a solvent must be completely removed therefrom to prevent it from penetrating into a layer superposed on the emulsion, such as the enteric material heretofore mentioned, whereby to prevent the introduction of coupler material into the superposed layer. If the developing agent is contained in this superposed layer, penetration of coupler therein enhances the possibilities for oxidation of the developing agent. Thus, while it is quite possible to introduce the coupler material into the emulsion layer, it is undesirable for the reasons just noted and including the fact that additional processing must be carried out to assure removal of the coupler solvent.

A developing agent in unoxidized condition will not seriously impair the sensitivity of a silver halide emulsion. With care, a developing agent may be incorporated in an emulsion without oxidation of the developing agent and may be retained in unoxidized condition provided the emulsion is quickly dried and is kept away from moisture until after exposure. Oxidation of a developing agent, as already pointed out, takes place readily in aqueous solution or under humid conditions. Hence, even if a developing agent is introduced into an emulsion without oxidation, some oxidation is likely to occur in storage or before use unless special packaging arrangements are employed or the emulsion is coated with a moisture-impermeable coating. The enteric materials heretofore mentioned, be cause they are relatively water impermeable, afford an ideal carrier for the developing agent and obviously permit avoidance of the additional processing and disadvantages which arise when the developing agent is incorporated in the emulsion layer itself.

At the sacrifice of the advantages derived from the use of an enteric material as a carrier for the coupler, the layer 15 in which the coupler is incorporated may be of a watersoluble and permeable character and may comprise polyvinyl alcohol, gelatin or a water-soluble film-forming material such as sodium carboxymethyl cellulose.

By a further embodiment of the invention, both the layer which contains the coupler or color former and the layer which contains the developing agent may be placed in back of the emulsion layer provided suitable precautions are taken to prevent intermingling of the coupler and the developing agent with each other as well as to prevent the coupler and developing agent from intermingling with the photosensitive emulsion until the liquid-processing composition has been released to process the film unit. These precautions may be effected by the employment of an enteric material as a carrier for both the developing agent and the color former. However, since it is difficult to cast a layer of an enteric material on another layer of enteric material, it is preferable to separate these layers by a stratum of permeable material, such as gelatin, on which an enteric material may readily be laid down.

A film unit or product embodying these characteristics is illustrated in Fig. 2 and as therein shown makes use of a negative sheet material or photosensitive element 20 comprising a conventional photographic support 21 which supports, in the order named, a layer 22 of an enteric material which has a developing agent dispersed therein, a gelatin layer 23, a layer 25 of an enteric material which contains coupler or color former and an emulsion layer 24.

Negative sheet material of the character illustrated in Fig. 2 requires manufacturing steps in addition to those needed for the formation of the unit illustrated in Fig. l and for this reason the unit of Fig. l is generally preferred.

In this embodiment, the positive image-receiving element 26 comprises an image-receiving or base layer 27 having a layer or stratum 28 of gelatin cast or coated thereon. The oxidizing agent used with the image-receiving element of Fig. 2 is incorporated substantially only in the gelatin layer 28.

A container 29 for liquid-processing composition is shown as carried on the emulsion layer 24. Fastening means, not shown, are utilized with the film unit of Fig. 2 for securing an end of the negative sheet material 20 to an end of the image-receiving sheet 26.

It may be noted that in the film unit disclosed in Fig. 2, the developing agent is still located in a position more distant from the emulsion layer than the layer which contains the coupler material. Thus, the advantages derived from such an expedient are present in the embodiments of the invention shown in both Figs. 1 and 2.

As in the embodiment of the invention disclosed in Fig. l, the layer 25 in which the coupler is dispersed may be formed of a water-soluble material such as gelatin. While such a construction obviates the need of the permeable stratum 23, the advantages derived from incorporating a coupler material in an enteric layer are lost.

In all embodiments of the invention, dye is preferably created by a coupling reaction between a coupler or color former and a secondary color-forming developing agent, i. e., a developing agent which when oxidized will react with a coupler to create a dye.

The invention is not limited to use with a single coupler in a permeable layer of the photographic element but in a further modification comprehends the incorporation in such layer of several different color formers whereby to give a positive image having a color different from each of the individual dyes formed upon coupling of the different color formers.

Color formers or couplers employed in the practice of the invention should be at least partially soluble and mobile in an alkaline aqueous solution, such as the liquidprocessing compositions hereinafter described. On the other hand, dyes resulting from the coupling of such color formers with a developing agent should be relatively insoluble or immobile in alkaline solution whereby dye formed in the sheet material which carries the photosensitive layer remains therein and its diffusion into the imagecarrying layer is substantially prevented. At the same time, the couplers employed should preferably have such solubility in alkaline solution that they do not dissolve therein to an extent whereby they migrate from the photographic negative material prior to initiation of the development reaction so that the color-former material will remain in the neighborhood of the developing silver halide grains whereby to guarantee coupling in the negative material wherever silver development takes place.

The couplers or color formers are preferably of a character which form azomethine, indaniline and indophenol dyes when reacted with a secondary color-forming developing agent which has been oxidized. Such couplers may comprise nitriles, acyl nitriles, thioindoxyls, cyanacetanilides, pyrazolones, phenols, naphthols, substituted ketones, esters and acyl acetanilides. As examples' of a few of the many couplers which may be used with the invention, specific mention may be made of those in the following list:

p-Nitrophenylacetonitrile Cyanacetophenone p-Nitrobenzoylacetonitrile Bromthioindoxyl Cyanaceto-p-naphthalide l-cyanacetan1inobenzthiazole l-phenyl-3-furyl-5-pyrazolone l-phenyl-3-methyl-5-pyrazolone Pentachlorophenol o-Hydroxydiphenyl 2,4-dichloro-6-cyclohexylphenol Hydroquinone monobenzyl ether 2,4-dichloro-l-naphthol Pentabromonaphthol 5,7-dibromo-8-hydroxyquinoline Benzoyl acetone fi-naphthoyl acetone Benzoyl acetic ester Acetoacetanilide Acetoacet-2-chloroanilide Ethyl acetoacetate Developing agents for use with these couplers comprise such secondary developing agents as the p-phenylenediamines, the aminophenols and their alkyl substituted derivatives, and others characterized by their ability when oxidized to condense with couplers to form dyes. Combinations of developing agents and couplers which form the least soluble and/or least mobile dyes are preferred since such combinations give the clearest highlights and the sharpest detail to the positive image.

A wide variety of oxidizing agents, adapted to be incorporated by imbibition in the image-carrying layer or in a gelatin coating thereon, are suitable for use in putting the invention into practice although their selection will be dependent upon their ability to oxidize the developing agent without substantially affecting the dye formed as a result of the color-forming reaction between oxidized developing agent and the coupler. Oxidizing agents which are of such powerful and strong nature that they seriously impair a dye of the character utilized by this invention, by bleaching or otherwise attacking the dye, are obviously unsuitable. As indicative of what is meant by powerful oxidizing agents reference is made to substances such as bromine, iodine, hydrochloric acid, chromic acid, nitric acid and the like.

As examples of oxidizing agents of a sufficiently weak character to be useful with this invention mention may be made of per-oxy compounds such as sodium or potassium perborate, sodium or potassium perchlorate, sodium or potassium peroxide, sodium or potassium permanganate, barium or zinc or cadmium peroxide and ammonium persulfate. Certain dichromates, for example, ammonium dichromate, are also useful for oxidizing agents. Particularly useful oxidizing agents may be found in the readily reducible compounds of the polyvalent heavy metals which have their polyvalent metallic element in higher valent form, and especially in the salts of such compounds. Examples thereof may be found in compounds of copper, antimony, uranium, manganese and iron wherein the metallic element is in higher valent form.

The compounds having polyvalent metallic elements in higher valent form are reduced by the unreacted developing agent which, as a result, becomes oxidized. At the same time, the reduced salt or other compound appears, at least in the case of compounds of copper, to display an afiinity for the dye formed upon coupling of the oxidized developing agent and color former and in this respect seems to act as a mordant. Whatever may be the action of these reducible compounds of polyvalent metals, the fact is that image density is increased over that obtained under a similar set of conditions but with the employment of other oxidizing agents.

The preferred polyvalent metallic compounds are cupric salts and as specific examples thereof cupric sulfate, chloride, acetate and stearate are noted. Of these examples of cupric salts, cupric sulfate is preferred. Cupric sulfate and potassium thiocyanate provide a highly useful oxidizing agent which may be introduced in the positive image-carrying layer 17 or the coating 28 by the successive imbibition of these materials in said element followed by washing. It is believed that as a result of this last-noted treatment, the positive element contains some cupric hydroxide and some copper thiocyanate.

In addition, aerial oxidation may be utilized for the purpose of oxidizing unreacted developing agent in or on the image-carrying or base layer to effect positive image formation. When such practice is followed, it is desirable to use a material for the image-carrying layer which contains a dye mordant. Material of this nature is found in conventional dye-transfer papers of which that sold by Eastman Kodak Company under the name Dye Transfer Double Weight F is a specific example. As other examples of image-receiving layers having a mordant, mention may be made of gelatin in which nickelous sulfdate or aluminum sulfate has been uniformly distribute The liquid-processing composition employed in carrying out the invention comprises at least an aqueous alkaline solution of sufficient alkalinity to permit the developing agent to perform its developing function. A viscosity-increasing compound constituting a film-forming material of the type which, when spread over a water-absorbent base, will form a relatively firm, solid film, is preferably included in the liquid-processing composition to assist in spreading the composition in a uniform film between the layers of the film units heretofore described. A preferred film-forming material is a high molecular weight polymer as, for example, a polymeric, water-soluble ether inert to an alkali solution such as hydroxyethyl cellulose or sodium carboxymethyl cellulose. Other film-forming materials or thickening agents may be employed when their ability to increase viscosity is substantially unaffected when left in solution for long periods of time. The film-forming material is preferably contained in the processing com osition in suitable quantities to impart to the composition a viscosity in excess of 1000 centipoises at a temperature of approximately 24 C. and preferably of the order of 1000 to 200,000 centipoises at said temperature.

Containers l9 and 29 may be formed from composite sheet material comprising an inner layer which is substantially chemically inert to the liquid composition used for processing the film unit, an intermediate layer which is substantially impervious to vapor, and an outer or backing layer which can be readilv adhered to some layer of the film unit. Materials for the inner layer of the containers 19 and 29 may be found among the polyvinyl acetals, of which polyvinyl butyral and polyvinyl acetal itself are examples, while the intermediate layer may comprise metal foil such as lead or silver foil and the outer layer may comprise a suitable paper such as kraft paper. A container may be formed by folding such a composite sheet upon itself, adhering the free edges of the folded sheet together at one end and on a side thereof and, after filling the container, sealing the open endh thereof by adhering the remaining free edges toget er.

The image-carrying or base layer 17 or 27 may be gelatin which is generally carried on a support, an example thereof being found in imbibition paper. Other excellent imagecarrying materials comprise papers such as those known in the art as baryta paper and dye transfer paper. In fact any material dyeable from alkaline solutions may be employed as an image-carrying layer, such materials including water-permeable plastics, or water-permeable, reversible, film-forming organic colloids capable of having high viscosity characteristics and appreciable jelly strength. Specific examples of other dyeable layers are regenerated cellulost; polyhydroxy alkanes, such as polyvinyl alcohol; sodium alginate; cellulose ethers, such as methyl cellulose, or other derivatives, such as sodium carboxymethyl cellulose or hydroxyethyl cellulose; papers; proteins, such as glue; carbohydrates, such as gums and starch; and mixtures of such materials Where they are compatible. When the above materials are transparent they may, if desired, be mounted on an opaque base, or, a colloidal pigment may be incorporated in such material to render the same opaque.

Support materials when employed to support an imagecarrying or base layer, may be any material of the character used as a support for conventional photographic film and papers. The materials mentioned as suitable for use as image-carrying layers may also be employed in conjunction with a photosensitive layer of the negative sheet material and as a support for the negative elements 10 and 20.

To thoroughly instruct the art in the practice of the invention, the following nonlimiting examples are set forth with reference to film units heretofore disclosed by way of giving details as to the materials employed in the construction and processing as well as particulars to techniques employed in color image formation:

EXAMPLE 1 Solution I 2 amino 5 diethylaminotoluene monohydrochloride grams 2.5 Methanol cc 5 Solution II Cellulose acetate hydrogen phthalate grams Acetone cc The coating or layer 12 formed by the mixed solutions I and II may be applied to the baryta paper by rollcoating practices. After being cast, layer 12 is dried.

It is to be noted that the developing agent is well protected against oxidation in Solutions I and II if impurities, such as water and organic peroxide, are substantially absent from the organic solvents employed in these solutions. Also, the mixture of Solutions I and II is safe in visible light but after coating should be kept from prolonged exposure to ultraviolet light. Likewise, it may be observed that the cellulose acetate hydrogen phthalate is acidic and is not very hygroscopic and hence affords some protection to the developing agent against oxidation.

Following the formation of the layer 12 containing the developing agent, a silver halide emulsion is doctored on the outer surface of said layer and is allowed to dry. A blue-sensitive emulsion may be employed and a relatively thick layer 14 thereof is formed.

The negative sheet material 10 is next coated with the following coupler solution:

2,4-dichloro-l-naphthol grams 0.3 Cellulose acetate hydrogen phthalate do 2.0 Methyl Cellosolve cc The layer 15 having coupler dispersed therein may be applied by merely flowing the coupler solution over the emulsion layer 14 and allowing the applied material to dry, this operation being carried out in darkness.

The positive image-receiving element 16 used with the above-described negative material 10 employs baryta paper to form the image-receiving layer 17. oxidizing agent is incorporated in the image-receiving layer 17 by immersing said layer for about one minute in a 0.25% cupric sulfate solution, following which the receiving sheet may be squeegeed and coated with clear gelatin, for example a 20% gelatin solution, and then dried.

The liquid composition for each container 19, in this specific example, comprises a predetermined quantity of a viscous alkaline aqueous solution and may be prepared by thoroughly mixing the following materials:

Sodium carboxymethyl cellulose grams 5 Sodium carbonate do Water cc. 100

In the use of the just-described embodiment of the invention, the photosensitive element or negative sheet material 10, while in a spread apart condition with respect to the positive image-receiving element 16, may be exposed and processed in suitable camera apparatus in the manner described whereby at least the exposed portion of the negative element 10 is brought into contact with at least a portion of the image-receiving element 16 of the film unit, and liquid in a container 19 adjacent the exposed area of the element 10 is released and spread in a uniform thin layer between the layer 15 containing color former and the layer 18 of gelatin.

When liquid-processing composition is spread between the layer 15 containing coupler and the positive imagereceiving element 16 following fracture of a container, processing composition migrates into layer 15, the emulsion layer 14 and the layer 12 containing developing agent from which latter layer it returns to the emulsion layer 14. During permeation into the layer 15, coupler contained in this layer is dissolved in liquid-processing composition and is transported in solution into the emulsion layer 14. Processing composition permeated into the layer 12 acts to dissolve developing agent in that layer and carries the developing agent in solution into the emulsion layer 14, thereby introducing both developing agent and coupler or color former in the exposed emulsion.

Where the developing agent reacts with exposed silver halide, it is oxidized as a function of the amount of silver halide reduced to silver and the developing agent thus oxidized couples with color-former material adjacent the developing silver grains to form a relatively immobile dye in the negative sheet material 10. In all modifications of the invention, developing agent present in a unit area of the layer, adapted to have the developing agent incorporated therein, is in a quantity just sufticient to be completely oxidized by a fully developable or completely exposed portion of the emulsion layer 14. Likewise in all modifications of the invention, coupler material available in the layer adapted to contain the coupler in a unit area, of the same magnitude as the previously mentioned unit area, is preferably of a quantity just sufficient to be entirely coupled by that amount of developing agent which is oxidized by the development of a completely exposed unit area of the emulsion layer.

Consequently, the coupler material is substantially exhausted by coupling with the oxidized developing agent in the area of the highlights of the negative image and is trapped in the negative sheet material of the photographic product. In places in the negative material where unexposed silver halide grains are present or in places where exposure and consequent development is less than complete, unoxidized developing agent and unreacted coupler material are in solution in proportion to silver development and are transported, at least in part, by imbibition to the image-carrying layer which is in such close proximity to the negative material as to receive a depthwise diffusion of liquid from the emulsion layer without appreciably disturbing the imagewise distribution of developing agent and coupler material provided by the development of the latent image in the emulsion layer. The unreacted developing agent and the unreacted coupler material are transferred in solution to the image-carrying layer where the unreacted developing agent is oxidized by the oxidizing agent in the image-carrying layer to initiate coupling with the unreacted color former material and to provide in the image-carrying layer a dye positive image which in this instance is cyan.

Imbibition time in Example 1, namely, the time the exposed negative element and image-receiving element 16 are kept in contact after the spreading of the liquidprocessing solution, is for about 5 minutes, following which the image-carrying layer is separated from the photosensitive element. As a result of the processing a cyan image, free from developer stain, was formed in the image-carrying layer. This image had good hue and contrast.

The separation of the negative element and the imagecarrying material may be accomplished by stripping action, and any coating of film-forming material from the processing composition adhering to the gelatin 18 may be removed or allowed to remain thereon. Image formation, while the negative and positive sheet materials are in contact, is carried out in light to which the photosensitive layer is substantially insensitive and may be conveniently carried out by keeping the film unit in the dark by allowing it to remain in the camera apparatus employed to expose it until formation of the dye positive image has been completed. Of course, in instances wherein the outer layers of the film unit are opaque to actinic light, the unit may be removed from camera apparatus after the liquid-processing composition has been spread and image formation allowed to proceed under ordinary lighting conditions.

The foregoing procedure possesses the advantage that the presence of excess developing agent in the positive image-receiving element is avoided in addition to the previously noted advantages which accrue from placing color former and developing agent each in an individual layer which is separated from the photosensitive layer, and by the employment of a processing compositlon which when released lacks components which can form a dye. Excess developing agent in the positive imagereceiving element is undesirable because it is a source which can give rise to stain in the highlights of the positive image. Since the developing agent is toxic to the human skin, excess thereof in the positive image-receiving element is also undesirable from the standpoint of the contact thereof with the hands when the positive image-receiving element is separated from the negative sheet material following formation of the positive image.

EXAMPLE 2 A film unit like that shown in Fig. l was formed by treatment similar to that set forth in Example 1 makmg use of solutions which contain coupler and developing agent and a processing composition differing from those of Example 1 in the manner immediately set forth.

In Example 2 the layer 12 containing the developing agent was cast from a mixture of the following solutions:

The layer containing coupler was cast in accordance with Example 2 from the followmg composition:

2,4-dichloro-l-naphthol grams 5 Cellulose acetate hydrogen phthalate do 2 Methyl Cellosolve ec 100 The liquid-processing composition for use in this example comprised: Sodium carboxymethyl cellulose grams 5 Sodium carbonate do 8 Water c 100 minutes.

EXAMPLE 3 In this example, negative sheet material 10, like that shown in Fig. l, was employed with a positive imagereceiving element 26 like that illustrated in Fig. 2 to provide a film unit.

The negative element in Example 3 was formed in the manner and of the materials set forth in Example 2.

However, in Example 3 a processing composition like that of Example 1 was employed.

For the positive image-receiving element 26 employed in this example, baryta paper was used as the imagereceiving layer 27 and this was coated with a 20% solution of clear gelatin to provide layer 28 after which the element 26 was treated, as by imbibition, with a 0.25% solution of cupric sulfate whereby to incorporate an oxidizing agent in the gelatin layer.

Following exposure, and with an imbibition time of about 5 minutes, a cyan image was produced with a film unit such as that described in Example 3 which compared favorably with the dye positive images of the preceding examples. With positive material 26 of the type shown in Fig. 2 and used in Example 3, a slight pinkish discoloration may appear around the edges of the image. Pinkish discoloration of this nature would seem to indicate a tendency of the sodium carbonate in the liquidprocessing composition to react with oxidizing agent in the gelatin. For this reason, it is preferred to use a positive image-receiving element like that of Fig. l wherein the oxidizing agent is located in the image-receiving layer with the result that contact of the processing composition with the oxidizing agent is slowed by the necessity of the composition having to penetrate through the gelatin.

The practice of the invention is not limited to the formation of cyan images. Monochromatic images of different colors, for example the other components of subtractive color systems, may be formed by the use of couplers selected to react with any oxidized secondary color-forming developing agent of the character heretofore mentioned to provide a dye of the desired color. In this regard, appropriate substitution of p-nitrophenylacetonitrile as the coupler material in Examples 1, 2 and 3 will result in the formation of a magenta image in each of those examples. Similarly, a yellow image may be obtained in Examples 1, 2 and 3 by employing acetoacet-Z-chloroanilide as a coupler.

As previously pointed out, dye positive images of a color other than those heretofore mentioned are obtainable when several couplers are employed in the photosensitive layer rather than a single coupler. The result of such expedient is to give a positive image having a color different from each of the individual dyes formed during processing. Thus, it is possible to form black and white dye positive images by the color forming of appropriate dyes which, when added together, give a black. The attributes of any color obtained in this manner is of course dependent upon the specific couplers employed and their proportions in the mixture. As an example, a bluish-gray and white positive image may be obtained by the use in any of the specific examples of a layer 15 or 25 which has a coupler mixture uniformly dispersed therein and comprising appropriate quantities of p-nitrophenylacetonitrile; 2,4 dichloro l napthol; and acetoacet-Z-chloroanilide.

It has been indicated that the unreacted developing agent in or on the image-carrying layer of a film unit may be oxidized by aerial oxidation. Thus, in all of the illustrative examples of the invention, it is possible to omit an oxidizing agent from the positive image-receiving element and to create a dye image therein by permitting air to effect oxidation of the unreacted developing agent in the imagewise distribution of the unreacted developing agent and the unreacted color-forming material in the image-carrying layer upon the separation of the image-carrying layer from the negative sheet material in the usual manner. Processing in this manner is comprehended by the invention, although the use of an oxidizing agent is preferred as it speeds up the oxidation reaction and renders it substantially complete.

Likewise, while a liquid container, such as the container 19 or 29, provides a convenient means for spreading a liquid composition between layers of a film unit whereby to permit the processing to be carried out within a camera apparatus, the practices of this invention may be otherwise elfected. For example, a photosensitive layer after exposure in suitable apparatus, and while preventing furthcr exposure thereof to actinic light, may be removed from such apparatus and permeated with the liquid-processing composition as by coating the composition on the photosensitive layer or otherwise wetting the layer with the composition, following which the permeated layer, still without exposure to actinic light, is brought into contact with an image-carrying layer for image formation in the manner heretofore described.

For the purpose of simplicity, the invention has been illustrated and described in connection with a film unit of the roll film type. The invention, however, is not limited to this type of film and may be employed with cut film in a film pack type of unit.

Throughout the specification and appended claims the expression positive image has been used. This expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive layer. As an example of an alternative meaning for positive image, assume that the photosensitive layer is exposed to actinic light through a negative transparency. In this case the latent image in the photosensitive layer will be a positive and the image produced on the image-carrying layer Will be a negative. The expression positive image is intended to cover such an image produced on the image-carrying layer.

In the preceding portions of the specification the expression color has been frequently used. This expression is intended to include the use of three colors to obtain black.

Throughout the specification and claims, the expression superposing has been employed. This expression is intended to cover the arrangement of two layers in overlying relation to each other either in face-to-face contact or in separated condition and including between them at least one layer or stratum of a material which may be a viscous liquid.

It is to be noted that while a high viscosity for the liquid-processing composition is desirable to assist in its spreading, the invention may be successfully practiced without the use of a film-forming material in the composition. As illustrative of this latter expedient, refer ence is made to the processing compositions of the preceding examples all of which are employable for processing purposes by the substitution of water for the sodium carboxymethyl cellulose in a quantity equivalent to such film-forming material. In instances when containers are not employed, a nonviscous processing composition is particularly applicable and may be applied to the negative material by imbibition or coating practices and may be similarly applied to the image-carrying layer before the latter and the negative material are brought into contact.

The invention finds particular utility in the field of color photography and, in addition to providing for the formation of monochromatic or images of a single color, is useful in providing multicolor images. As one example of the utility of the invention in the multicolor field, two or more transparent image-carrying layers, each containing an individual color component image of a multicolor image, may be assembled in superposed and registered relation on a common support in a manner well understood by the art whereby to provide the desired multicolor image.

As another example, the invention is adaptable for multicolor Work carried outwith special film units wherein two or more appropriately sensitized layers are associated with a like number of image-carrying layers. In lieu of this practice, tripack film prepared with coupler and developing agent in the manner herein set forth, may be employed as negative material and, after exposure, each layer thereof may be developed and treated in accordance with the preceding disclosures in conjunction with individual image-carrying layers.

As a further example in this regard, a plurality of dye component images may be formed in the same image carrying layer by successively bringing the image-carrying layer into registered contact with individual negative elements, each of which latter contains a negative latent image representative of a positive color component image to be formed in the image-carrying layer. In such practice, the image-carrying layer may, if desired, be retreated with a solution of an oxidizing agent during the course of processing and intermediate the formation of a successive pair of positive color component images.

Furthermore, the invention is useful for copying purposes from separation positives with any of the types of film units described. Of course when the invention is used in the production of photographic originals, the spectral sensitivity of the difierent emulsion layers must be suitably chosen. For instance, instead of using a blue sensitive emulsion, a panchromatic or a specially red sensitized emulsion is employed for producing a cyan positive image. However, for copy work from separation positives, this is obviously unnecessary.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a process of forming positive images in color from a negative latent image in a silver halide emulsion layer of a photosensitive element wherein said photosensitive element, in addition to silver halide, contains a silver halide developer having an oxidation product reactable with coupler material to form image dye and wherein said photosensitive element also contains coupler material reactable with oxidized developer to provide said dye, the steps comprising applying to one side of said photosensitive element a liquid which is a solvent for said developer and coupler but Which is substantially free of developer and coupler upon its application, permeating said applied liquid through said emulsion layer by absorbing said liquid into said photosensitive element, dissolving coupler material in liquid present in said photosensitive element as a result of the absorption of said applied liquid and dissolving developer substantially only in liquid which has permeated through said emulsion layer as a result of absorption into said photosensitive element and forming in said emulsion layer a substantially uniform distribution of unreacted developer and unreacted coupler material in solution in said liquid whereby to develop said latent image to silver and form a dye image in situ therewith while providing an imagewise distribution of unreacted developer and unreacted coupler material in said emulsion layer, transferring from said emulsion layer by imbibition at least part of said imagewise distribution of unreacted developer and unreacted coupler material to an imagecarrying layer superposed with said photosensitive element in such close proximity thereto as to receive a depthwise diffusion of liquid from said emulsion layer without appreciably disturbing the imagewise distribution of compo nents contained in said liquid, oxidizing said transferred developer in said image-carrying layer, and reacting the oxidized product with said unreacted coupler material in said image-carrying layer to form a dye whereby to provide a positive image of said latent image.

2. The process of forming positive images in color from a negative latent image contained in a silver halide emulsion layer of a multilayered photosensitive element having a permeable layer containing a silver halide developer and another permeable layer containing a coupler material arranged in superposed relation to said emulsion layer so that a liquid applied to one side of said photosensitive element must, upon absorption into all of said layers, pass through said emulsion layer prior to penetration into said layer containing developer, said silver halide developer being characterized by having an oxidation product which is reactable with coupler material to form image dye and said coupler material being reactable with oxidized developer to provide said dye, applying coextensively over said side of said photosensitive element and absorbing into all of said layers a liquid which is a solvent for said developer and for said coupler whereby to form in said emulsion layer a disposition of developer and coupler material in solution in said liquid and to develop said latent image to silver and provide a dye image in situ therewith whue providing in sald emulsion layer, as a result of the development or silver and image dye, an imagewise distribution of unreacted developer and unreacted coupler material, at some stage of said process bringing said photosensitive element and an image-carrying layer into overlying relation with said side or said photosensitive element positioned substantially in contact with said image-carrying layer and transferring from said assembly and to said image-carrying layer by imoibition at least part of said imagewise distribution of unreacted developer and unreacted coupler material while maintaining said imagecarrying layer and said assembly in such close proximity as to receive a depthwise diffusion of liquid from said assembly without appreciably disturbing the imagewise distribution of components contained in said liquid, and oxidizing said transferred developer in said image-carrying layer and reacting the oxidized product with said unreacted coupler material in said image-carrying layer to form a dye.

3. The process of forming positive images in color as defined in claim 2 wherein the image-carrying layer and the photosensitive element are separated from superposed relationship at some stage of said process after the imagewise distribution of unreacted developer and unreacted coupler material has been transferred from the emulsion layer of said photosensitive element to said image-carrying layer.

4. The process of forming positive images in color which comprises bringing a sheet material comprising at least an image-carrying layer into overlying relation with one side of a photosensitive element having a plurality of superposed layers which include a silver halide emulsion layer having a negative latent image therein, a permeable layer containing coupler material and another permeable layer which contains a silver halide developer and which, of all said layers of said photosensitive element, is positioned furthest away from said side of said element, and spreading a liquid, which is a solvent for said developer and coupler material, in a layer between and in contact with said image-carrying layer and said side of said photosensitive element, said silver halide developer being characterized by having an oxidation product which is reactable with coupler material to form image dye and said coupler material being reactable with oxidized developer to provide said dye, maintaining said photosensitive element and said image-carrying layer in said overlying relation and absorbing liquid into said photosensitive element and permeating said liquid within each layer of said element, including said layer containing said developer, to effect the solution of developer substantially only in liquid which is permeated through said emulsion layer and the solution of coupler material in liquid which is absorbed into said photosensitive element whereby to form in said emulsion layer a substantially uniform disposition of developer and coupler material in solution in said liquid and to develop said latent image to silver and provide a dye image in situ therewith while providing in said emulsion layer, as a result of the development of silver and image dye, an imagewise distribution of unreacted developer and unreacted coupler material, and, while maintaining said image-carrying layer and said photosensitive element in said overlying relation, transferring from said emulsion layer by imbibition at least part of said imagewise distribution of unreacted developer and unreacted coupler material to said image-carrying laver to provide in the image-carrying layer a depthwise diffusion of liquid from said emulsi n layer without appreciably disturbing the ima ewise distribution of components contained in said liquid, and oxidizing said transferred developer and reacting it with transferred coupler material in said imagecarrying layer to form a dye whereby to provide a positive image of said latent image.

5. The process of forming positive images in color as defined in claim 4 wherein said liquid contains a thickener for increasing viscosity and for facilitating the spreading thereof between said photosensitive element and said sheet material.

6. The process of forming positive images in color as defined in claim 4 wherein the image-carrying layer and the photosensitive element are separated from superposed relationship at some stage of said process after the imagewise distribution of unreacted developer and unreacted coupler material has been transferred from the emulsion layer of said photosensitive element to said image-carrying layer.

7. The process of forming positive images in color as set forth in claim 2 wherein said liquid is introduced into said photosensitive element by bringing the liquid into contact with a surface of the said layer which contains coupler material whereby said permeated liquid comprises a solution of coupler material prior to the introduction of developer therein.

8. T he process of forming positive images in color as set forth in claim 4 wherein said liquid is spread between and in contact with said sheet material and the layer of said photosensitive element which contains coupler material whereby said permeated liquid contains coupler material in solution prior to having said developer introduced therein.

9. The process of forming positive images in color as defined in claim 4 wherein said liquid contains a thickener for increasing viscosity and for facilitating the spreading thereof between said photosensitive element and said sheet material, and wherein said liquid is spread between and in contact with said sheet material and the layer of said photosensitive element which contains coupler material whereby said permeated liquid contains coupler material in solution prior to having said developer introduced therein.

10. The process of forming positive images in color as defined in claim 4 wherein the image-carrying layer and the photosensitive element are separated from superposed relationship at some stage of said process after the imagewise distribution of unreacted developer and unreacted coupler material has been transferred from the emulsion layer of said photosensitive element to said image-carrying layer, and wherein said liquid is spread between and in contact with said sheet material which includes said imagecarrying layer and the layer of said photosensitive element which contains coupler material whereby said permeated liquid contains coupler material in solution prior to having said developer introduced therein.

ll. A photographic product comprising a multilayered photosensitive element having a silver halide emulsion layer, a permeable layer which contains a silver halide developer, the oxidation product of which is reactable with coupler material to provide image dye, and another permeable layer which contains a coupler material reactable with oxidized developer to form image dye, said layers of said photosensitive element being arranged in superposed relation, a base layer for receiving a transfer image, and a container holding a liquid solvent for said developer and for said coupler material, said photosensitive element, said base layer and said container being held together to permit at least a portion of said base layer and said photosensitive element to be superposed with said container so positioned as to be capable of being ruptured and, without removal of its ruptured portion, of releasing its liquid content between said photosensitive element and said base layer to at least partially permeate the superposed base layer and photosensitive element including the emulsion layer, the layers containing developer and said coupler material being rendered effective to develop a latent image in said emulsion layer and form image dye therein upon release of said liquid, the result of development of the emulsion layer being the formation therein of a differential disposition of unreacted developer and unreacted coupler material which is adapted to be transferred to said base and to effect the formation of a reversed dye image of the subject matter of said latent image, said layer having developer therein being positioned with respect to the other layers of said photosensitive element so that it will be located on that side of the emulsion layer which will be furthest removed from said base layer when said photosensitive element and said base layer are in superposed position.

12. A photographic product as defined in claim 11 wherein an oxidizing agent, which is substantially inactive with respect to image dye, is substantially and uniformly distributed at least throughout a stratum of said base layer.

13. A photographic product as defined in claim 11 wherein said base layer has an oxidizing agent which is substantially inactive with respect to image dye distributed uniformly therein and wherein a stratum of a relatively permeable material is mounted on the base layer on that surface thereof which is adapted to be positioned adjacent said photosensitive element.

14. A photographic product as set forth in claim 11 wherein said layer, having coupler material contained therein, forms that side of the photosensitive element adapted to be positioned directly adjacent said base layer when said photosensitive element and said base layer are in superposed relation to each other.

15. A photographic product as set forth in claim 11 wherein the layer containing coupler material and the layer containing developer are located on opposite sides of said emulsion layer with the layer containing developer so located that it is more distant from said base layer than said layer containing coupler material when said photosensitive element and said base layer are superposed, and wherein said base layer has an oxidizing agent which is substantially inactive with respect to image dye incorporated therein.

16. A photographic product as defined in claim 11 wherein said layer containing coupler material is located on one side of said emulsion layer and said layer containing developer is located on the other side of said emulsion layer with said layer containing coupler material being located so that it may be brought into contact with said base layer when said photosensitive element and base layer are superposed, and wherein an oxidizing agent which is substantially inactive with respect to image dye is distributed in said base layer and a stratum of relatively permeable material is carried on that surface of the base layer adapted to be positioned directly adjacent said photosensitive element.

17. A photographic product as set forth in claim 11 wherein said layer which contains coupler material and said layer which contains developer are located on that side of the emulsion layer adapted to be furthest removed from said base layer when said photosensitive element and base layer are superposed.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,034 Sease et al Aug. 31, 1943 2,347,119 1944 2,350,380 1944 2,363,764 1944 2,369,171 1945 2,386,167 1945 2,397,452 1946 2,500,421 1950 2,543,181 1951 2,565,377 1951 FOREIGN PATENTS 716,119 France Oct. 6, 1931 503,824 Great Britain Apr. 11, 1939 503,873 Great Britain Apr. 17, 1939 OTHER REFERENCES Ricketts: British Journal of Photography, June 5, 1914, page 446. 

1. IN A PROCESS OF FORMING POSITIVE IMAGES IN COLOR FROM A NEGATIVE LATENT IMAGE IN A SILVER HALIDE EMULSION LAYER OF A PHOTOSENSITIVE ELEMENT WHEREIN SAID PHOTOSENSITIVE ELEMENT, IN ADDITION TO SILVER HALIDE, CONTAINS A SILVER HALIDE DEVELOPER HAVING AN OXIDATION PRODUCT REACTABLE WITH COUPLER MATERIAL TO FORM IMAGE DYE AND WHEREIN SAID PHOTOSENSITIVE ELEMENT ALSO CONTAINS COUPLER MATERIAL REACTABLE WITH OXIDIZED DEVELOPER TO PROVIDE SAID DYE, THE STEPS COMPRISING APPLYING TO ONE SIDE OF SAID PHOTOSENSITIVE ELEMENT A LIQUID WHICH IS A SOLVENT FOR SAID DEVELOPER AND COUPLER BUT WHICH IS SUBSTANTIALLY FREE OF DEVELOPER AND COUPLER UPON ITS APPLICATION, PERMEATING SAID APPLIED LIQUID THROUGH SAID EMULSION LAYER BY ABSORBING SAID LIQUID INTO SAID PHOTOSENSITIVE ELEMENT, DISSOLVING COUPLER MATERIAL IN LIQUID PRESENT IN SAID PHOTOSENSITIVE ELEMENT AS A RESULT OF THE ABSORPTION OF SAID APPLIED LIQUID AND DISSOLVING DEVELOPER SUBSTANTIALLY ONLY IN LIQUID WHICH HAS PERMEATED THROUGH SAID EMULSION LAYER AS A RESULT OF ABSORPTION INTO SAID PHOTOSENSITIVE ELEMENT AND FORMING IN 